Mechanism for gas operated gun

ABSTRACT

The tubular bolt of a paintball gun communicates with a cylinder through bores when in a forward, firing position, allowing compressed gas from the cylinder to expel a paintball. In accordance with the invention a bore whereby the cylinder communicates with a source of compressed gas is occluded by the bolt when the bolt is in the firing position. By this arrangement only gas stored in the cylinder is used to fire a paintball and the source of compressed gas is not in communication with the cylinder except when the trigger is released and the bolt is in its retracted position.

This application is a continuation of co-pending application Ser. No.10/870,687 filed Jun. 17, 2004 which was a continuation-in-part ofapplication Ser. No. 10/775,756 filed Feb. 9, 2004 now U.S. Pat. No.6,986,343. This application also claims priority from Britishapplications 0327683.9 filed Nov. 28, 2003, 0404989.6 filed Mar. 5, 2004and 0408954.6 filed Apr. 21, 2004.

FIELD OF THE INVENTION

This invention relates to an improved mechanism for a gas operated gun,by which is meant a gun of the type which fires a projectile by means ofcompressed gas. Guns of this kind are used in paintball games. Balls ofpaint are fired at other players to mark them.

BACKGROUND OF THE INVENTION

Conventional paintball guns have a hollow bolt which, when the triggeris pulled to file the gun, is moved from a rear to a forward position inthe barrel, in the process selecting and moving forward the lowermostpaintball in a magazine above the barrel. In the forward position of thebolt bores opening to its interior are exposed to compressed gas in acylinder surrounding the bolt, causing the selected paintball to beexpelled from the gun. When the trigger is released the bolt is movedback to its rear position, in which the bores are isolated from thecylinder.

A disadvantage of this otherwise simple arrangement is that more gas isused every time the gun is fired than is necessary to expel the selectedpaintball. Consequently the source of compress gas, usually an aircylinder fitted to the gun housing, has to be replaced quite frequently,which is an expense and inconvenience.

U.S. Pat. No. 5,613,483 seeks to address this problem by attaching aspool valve to the rear of the bolt. A fill and a dump chamber arepositioned in the gun housing behind the bolt. In the rear position ofthe bolt both chambers are filled with compressed gas, but when the boltmoves forward the spool valve isolates the chambers so that only the gasstored in the dump chamber escapes through the hollow bolt to fire theselected paint ball. A drawback of this gun is its complexity andrelatively high manufacturing and maintenance costs.

A principal object of the present invention is to provide a simplersolution to the problem addressed by U.S. Pat. No. 5,613,483 allowingconventional paintball guns to have the advantages of the gun of thatPatent as a result of a simple modification.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided a mechanismfor a gas operated gun having a housing and a trigger, the mechanismcomprising a sleeve fixed relative to the housing, a hollow boltslideable in the sleeve between a firing position when the trigger ispulled and a retracted position when the trigger is released and acylinder in the sleeve surrounding the bolt, the bolt being adapted whenin the retracted position to permit communication between the cylinderand a source of fluid under pressure while isolating the cylinder fromthe interior of the bolt and when in the firing position to isolate thecylinder from said source while communicating the cylinder with theinterior of the bolt.

The bolt may be slideable on an air fill tube fixed relative to thehousing, an O-ring seal being provided between the tube and the bolt,the tube having one or more radial opening rearward of said seal incommunication with said source and the bolt having one or more radialopening which will move from one side to the other of said seal as thebolt moves between its firing and retracted positions, the arrangementbeing such that in the retracted position of the bolt the cylindercommunicates with said source through the openings in the tube and boltwhile the seal prevents communication between the cylinder and theinterior of the bolt and such that in the firing position of the boltthe opening in the tube is occluded by the bolt and the opening in thebolt communicates the cylinder with the interior of the bolt.

Alternatively the sleeve may have a radial opening isolated from thecylinder in communication with said source and the bolt may have acircumferential recess positioned and dimensioned so that only when thebolt is in its retracted position the recess will communicate said portwith the interior of the cylinder.

Said port may be located in the sleeve rearwardly of the cylinder andmay communicate with said source via a passageway external to thecylinder and extending axially thereof.

In yet another embodiment of the invention a radial bore is provided inthe sleeve isolated from the cylinder and in communication with saidsource, the outer periphery of the bolt having an axially elongatedcircumferential depression which in the retracted position of the boltcommunicates said bore with the cylinder, the arrangement being suchthat in the firing position of the bolt said bore is occluded by thebolt while the cylinder is communicated with the interior of the bolt.The cylinder may have front and rear openings to the bolt, the frontopening aligning with an opening of the bolt in the firing position ofthe latter and the rear opening aligning with said depression in theretracted position of the bolt.

Alternatively the cylinder may be open to the bolt throughout its lengthand said opening of the bolt may take the form of a circumferentialarray of holes in the bolt which will be exposed to the cylinder in thefiring position of the bolt.

Means for displacing the bolt between its firing and retracted positionsmay surround the bolt in front of or behind said cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates part of the mechanism of a paintball gun according toa first embodiment of the invention showing the bolt in its forward orfiring position;

FIG. 2 illustrates the mechanism of FIG. 1 showing the bolt in its rearor withdrawn position;

FIG. 3 illustrates part of the mechanism of a paintball gun according toa second embodiment of the invention showing the bolt in its rear orwithdrawn position;

FIG. 4 illustrates the mechanism of FIG. 3 showing the bolt in itsforward, firing position;

FIG. 5 illustrates part of the mechanism of a paintball gun according toa third embodiment of the invention showing the bolt in its forward orfiring position, and

FIG. 6 illustrates the mechanism of FIG. 5 showing the bolt in its rearor withdrawn position.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring first to FIGS. 1 and 2, a paintball gun has a hollow, tubularbolt 10 which is slideable on a guide 11 fixed cantilever fashion to therear of the gun housing (not shown) by its head 12. Surrounding the boltand bolt guide is a mechanism 13 which serves to move the bolt 10forward when the trigger (not shown) of the gun is pulled and rearwardwhen the trigger is released. In the example illustrated this mechanism13 works by placing a compressed gas canister (not shown) fitted to thegun selectively in communication with bores 14 and 15 whereby lands onthe bolt will be driven in one direction or the other. This arrangementis conventional and so will not be further described, except to say thatcompressed gas actuation of the bolt may be replaced by an electronicsystem.

Forward of the mechanism 13 a cylinder 16 surrounds the bolt and boltguide. The cylinder extends beyond the distal end of the bolt guide 11so that in the forward position of the bolt (FIG. 1) an array ofcircumferentially spaced radial bores 17 of the bolt exposes theinterior of the bolt to the interior of the cylinder 16. In thewithdrawn position of the bolt (FIG. 2) however the bores 17 are betweenO-ring seals 24 in axially spaced circumferential grooves 18 and 19 ofthe bolt guide 11 and therefore occluded from the cylinder 16.

A port 20 at the rear of the cylinder 16 is in communication with thecanister via a passageway 21 external to the cylinder and extendingaxially thereof. In accordance with a preferred embodiment of theinvention the port 20 takes the form of a circumferential slot in aradial formation 22 at the rear of the cylinder dimensioned such that itis in contact with the periphery of the bolt 10 except when it is inregister with a circumferential recess 23 in the bolt periphery. Thisoccurs when the bolt 10 is in its withdrawn position (FIG. 2) and therecess 23 has a length axially of the bolt such that it permitscommunication of the port 20 with the interior of the cylinder 16.Therefore so long as the trigger of the gun is not pulled the cylinder16 is charged with compressed gas which cannot escape to the interior ofthe bolt. When the trigger is pulled and the bolt 10 moves forward(FIG. 1) the charge of compressed gas can escape from the cylinder 16through the bores 17 to the interior of the bolt 10, but meanwhile theport 20 is occluded by the periphery of the bolt because the recess 23has moved forward. As is known per se the bolt 10 as it moves forwarddisplaces in to the barrel of the gun the lowermost paintball in amagazine (not shown) mounted above the gun and the selected paintball isfired from the gun by the compressed gas escaping from the cylinder 16.When the trigger is released and the bolt 10 is moved back the cylinder16 is isolated from the interior of the bolt and is recharged withcompressed gas as soon as the recess 23 comes back into register withthe port 20.

In the alternative embodiment of the invention illustrated in FIGS. 3and 4 like parts have like references but with the suffix A. Thearrangement is generally similar to that of FIGS. 1 and 2 except thatthe firing mechanism is positioned behind the bolt-moving mechanism andnot in front of it.

A bolt 10A is slideable within a sleeve 13A between the positions shownin FIGS. 3 and 4. Bores 14A and 15A alternatively communicate with acanister of compressed air (not shown) to move the bolt 10A forward orback.

In a rearward part of the sleeve 13A is a chamber 16A in whichcompressed gas from the canister is stored when, in the rearwardposition of the bolt (FIG. 3) an axially elongated circumferentialdepression 23A in the periphery of the bolt communicates a bore 20A withan opening 16B which opens from the chamber 16A to the inner peripheryof the sleeve 13A.

When the bolt is moved forward to the position of FIG. 4 the chamber 16Ais isolated from the bore 20A and an array of radial bores 17B in thebolt comes into alignment with openings 17A of the chamber 16A to theinner periphery of the sleeve 13A. Thus compressed gas in the chamber16A escapes to the interior of the bolt 10A to fire a paintball.

A third embodiment of the invention is illustrated in FIGS. 5 and 6. Thearrangement is similar to that of FIGS. 1 and 2 and like parts have likereferences but with the suffix B.

A bolt 10B is slideable within a sleeve 13B between the positions shownin FIGS. 5 and 6. Bores 14B and 15B alternatively communicate with acanister of compressed air (not shown) to move the bolt 10B forward orback.

The bolt 10B is slideable on a guide 11B similar to the guide 11 of theembodiment of FIGS. 1 and 2, but in this case the guide 11B selves as anair fill tube. It has a longitudinal bore 11C at the head 12B endcommunicating with the gas canister via a radial bore 11D and near tothe other end of the guide 11B communicating with a circumferentialarray 100 of radial bores which open to the periphery of the guide 111B.It will be observed that the bores 100 open to the periphery of theguide 111B between the O-ring seals in their respective grooves 18B and19B. In the firing position of the bolt 10B (FIG. 5), therefore, thebores 100 are occluded by the bolt and the cylinder 16B is isolated fromthe gas canister. However in the retracted position of the bolt 10B(FIG. 6) the bores 17B in the bolt have passed from a position in frontof to a position behind the O-ring in groove 18B and are therefore incommunication with the bores 100. Thus the cylinder 16B is placed incommunication with the gas canister while at the same time it isisolated from the interior of the bolt 10B.

In a conventional paintball gun the equivalent of the cylinder 16, 16Aor 16B is permanently in communication with the gas canister so that gaswill escape through the bolt 10, 10A or 10B for as long as the latterremains in its forward, firing position. Such a gun can be readilymodified in accordance with the present invention to ensure that whenthe gun is fired only compressed gas stored in the cylinder 16, 16A or16B will escape.

1. A mechanism for a gas operated gun having a housing and a trigger,the mechanism comprising a sleeve (13) in communication with a cylinder(16), the cylinder forming a gas chamber; a hollow bolt (10) having aninterior and exterior, slideable in the sleeve and cylinder between afiring position when the trigger is pulled and a retracted position whenthe trigger is released; the bolt being adapted when in the retractedposition to permit gas communication between the cylinder and a sourceof gas under pressure while isolating the cylinder from the interior ofthe bolt, and when in the firing position isolating the cylinder fromthe source of gas while allowing gas communication from the cylinder tothe interior of the bolt.
 2. The mechanism as claimed in claim 1 whereinthe bolt (10) is slideable on a guide (11), on O-ring seal (24) beingprovided between the guide and the bolt, the guide having gascommunication rearward of the seal with the source; the bolt having oneor more radial openings (17) which move from a first side of the seal toa second side of the seal when the bolt moves between its firing andretracted positions, whereby gas enters the cylinder from the source inthe retracted position but not the interior of the bolt, and gas movesfrom the cylinder to the interior of the bolt in the firing position. 3.The mechanism as claimed in claim 1 wherein the sleeve (13) has a radialopening (20) in gas communication with the source, the opening allowinggas to enter the cylinder (16) through a circumferential recess (23) inthe bolt (10) when the bolt is in its retracted position.
 4. Themechanism as claimed in claim 3 wherein the opening (20) is located inthe sleeve (13) rearwardly of the cylinder (16) and communicates withthe source via a passageway (21) external to the cylinder and extendingaxially thereof.
 5. The mechanism as claimed in claim 1 furthercomprising a radial bore (21) in the sleeve (13) isolated from thecylinder (16) and in communication with the source, wherein the outerperiphery of the bolt (10) has an axially elongated circumferentialdepression (23) which, in the retracted position of the boltcommunicates the bore with the cylinder, and in the firing position ofthe bolt occludes communication between the radial bore and the cylinderwhile the cylinder communicates with the interior of the bolt through atleast one radial opening (17).
 6. The mechanism as claimed in claim 5wherein the bolt (10) contains a plurality of radial openings thatcommunicate with the cylinder (16) in the firing position of the bolt.7. The mechanism claimed in claim 1 wherein the cylinder (16) is open tothe bolt (10) throughout the length of the cylinder and wherein theopening into the bolt is a circumferential array of holes in the boltwhich are exposed to the cylinder in the firing position of the bolt. 8.The mechanism as claimed in claim 1 wherein a means (13) for displacingthe bolt (10) between its firing and retracted positions partiallysurrounds the bolt.
 9. A gas operated gun mechanism comprising a hollowbolt (10) having an interior and exterior moving longitudinally in acylinder (16) between a forward firing position and a retractednon-firing position where the interior of the bolt gas communicates withthe cylinder when the bolt is in the firing position and cannot gascommunicate with the cylinder when the bolt is in the retractedposition.
 10. The gas operated gun mechanism of claim 9 furthercomprising a radial compartment (21) surrounding the cylinder, whereinthe radial compartment gas communicates with a gas source, and whereinthe radial compartment also gas communicates with the cylinder when thebolt is in the retracted position and cannot gas communicate with thecylinder when the bolt is in the firing position.
 11. The gas operatedmechanism of claim 9 wherein the interior of the bolt gas communicateswith the cylinder via at least one hole in the bolt.
 12. The gasoperated mechanism of claim 11 further comprising a plurality of radialholes in said bolt wherein the interior of the bolt gas communicateswith the cylinder.
 13. The gas operated mechanism of claim 10 whereinthe radial compartment (21) communicates with the cylinder (16) via acircumferential depression (23) in the exterior of the bolt (10).